Hydraulic controlled hitch



Oct. 15, 1963 l-i. R. BENFORD HYDRAULIC ooNTRoLLED HITCH 5 Sheets-Sheetl Filed 001'.. 30, 1959 0ct. 15, 1963 H. R. BENFORD HYDRAULIC CONTROLLEDHITCH Filed Oct. 30, 1959 Zva/E/voes TO EN EV @M5L @GW 0ct. 15, i963 H.R. BENFORD HYDRAULIC coNTRoLLED HITCH 5 Sheets-Sheet 3 Filed Oct. 50,1959 jvvs/vro es 0 bsp? MAE/Naf u Jae afa PMOND 55N of@ Get. 15, 1963 H.R. BENFORD HYDRAULIC CONTROLLED HITCH Filed Oct. 30, 1959 105 val 5Sheets-Sheet 4 Oct. 15, 1963 H. R. BENFORD 3,106,966

HYDRAULIC CONTROLLED HITCH Filed OCT.. 50, 1959 Z'N VEA/roes En b527-Mne/ No/ N l-/A ecu-D Pny MON@ BEA/poen .4r-ro @N EY United StatesPatent O 3,106,966 HYDRAULIC CUNTRQLLED HEFCE Harold R. Benford,Hexthorpe, Doncaster, Engiand, as-

signor to International Harvester Company, hicago, El., a corporation ofNew .iersey Filed Oct. 30, 19533, Ser. No. 849,334 4 Claims. (Cl. 172-9)This invention relates to tractors employing implementattaching linkageand in particular to a hydraulic power lift system for operating andcontrolling the implementattaching linkage.

This is an improvement of hydraulic Ipower lift systems as shown in U.S.Patent 3,014,536.

In all power lift systems wherein the implement-attaching linkage issupported at an elevated or transport position *by the power lift,maintenance of the linkage at the selected position depends on theestablishment of a hydraulic lock preventing any release of hydraulicfluid from the ram cylinder of the power lift. Any leakage of hydraulicfluid through the control valve means will result in ygradual loweringof the linkage from the selected elevated position, with consequentdanger of damage to an implement carried by the linkage. It iswell-known that in power lift systems having alternative positioncontrol, the action of the cam in the position control arrangement willfunction to move the control valve means to the lifting position if theimplement-attaching linkage falls below the selected position determinedby the setting of the position control, thereby safeguarding againstinadvertent lowering of the linkage due to leakage from the ram cylinderof the power lift.

The invention has for its object to provide improvements in the controlvalve means of the power lift system whereby the depth-limiting controlmay Vfunction to compensate for any leakage occurring in the controlvalve means.

FIG. 1 is a longitudinal section of a power lift system as described andembodying a depth-limiting control in conjunction with automatic draftcontrol means; and

FIG. 2 is a detail section of the improved control valve means accordingto the invention for use in the power lift system shown in FIG. 1.

lFIG. 3 is an end elevation corresponding to FIG. l, rbut drawn to anenlarged scale;

FIG. 4 is a detail section of the control valve means on the line v-z'v,FIG. 3;

FIG. 5 is a detail section on the line v-v, FIG. 3.

In carrying the invention into eifect according to one embodiment, andas illustrated in the accompanying diagrammatic drawings, the hydraulicpower lift system of a tractor is housed in a casing 1 lwhich supports acrossshaft 2 provided with externally arranged lift arms (not shown) andan operating arm 3 connected to a rod i coacting with a piston 5disposed in a ram cylinder 6 of the power lift. The casing 1 is providedat the rear end with a housing 7 supporting a transverse pivot 8 for abell crank lever 9 having an upper forwardly extending arm 10 coactingwith a verticallydisposed draft load reaction spring 11 and adapted atthe lower end of the forwardly extending arm for the pivotal connectionat 12 of the top link of a three-point linkage.

The control valve means in the form of a unit 13 is formed integrallywith an end plate 14 for the Casin-g 1, which end plate 14 also carriestheram cylinder 6 held in position by a cap member 1S. 'I'he valve unit13 comprises a main control valve member 16 in the form of a plungerhaving axially spaced lands 16a, lob. A passage 17 communicates betweenthe ram cylinder and a passage 18 in the valve unit. When the valvemember 16 is moved from the neutral position shown in the lCe drawingsto the left for operating the power lift to lower an implement carriedby the attaching linkage, the passa-ge 13 is placed in communicationwith -a space 20 by way of passages 101, 102, port (when valve member 92is in open position), 98, and 19, and thence through a port 21 with apassage 22 communicating with a reservoir within the casing 1.

Hydraulic fluid supplied from a continuously operating hydraulic pump Pis delivered through a pipe 23a to an inlet connection 23 and thencethrough a passage 24 to a by-pass valve arrangement including a ball orother valve member 25 which is normally held off its seating so as toestablish a low pressure by-pass condition for the hydraulic fluiddelivered through the passa-ge 24, the fluid passing out from theby-pass valve through a passage 26 and through passages 27, 28 forreturn to the reservoir.

The valve member 25 of the by-pass valve is normally held off itsseating by a piston 29 maintained in the position shown in the drawingsby pressure of fluid admitted from the passage 24 thr-ough an adjustablerestriction 30 and passages 31, 32 to the cylinder space 33 behind thepiston 29. The piston 29 consists of cylinder housing 23a containing aspring 291; and a plunger 29e which is urged by spring 29h outwardly ofthe housing 29a against ball valve 25 which is urged against theopposing spring loaded member 25b when fluid is trapped in space 33permitting the main body of the uid to bypass from passage 24 to`chamber 24a, port 24h to chamber 33a and into passage 26 therein topassages 27 and 28 to the reservoir. A passage 34 also communicatingwith the space 33 leads to a port 35 controlled by the land 16a of thevalve member 16 in such manner that, when the valve member 16 is movedfrom the neutral position shown to the right for ioperating the powerlift to lift the implement, fluid can escape from the cylinder space 33through the passage 34, port 35 and passage 36 to the reservoir. Onrelease of pressure in the space 33 acting on the piston 29, the valvemember 25 of the by-pass valve will be closed or seated against surfaces25e of valve seat 25d by the action of a spring 25a, the piston 29ibeing correspondingly displaced to the left. On closing of the by-passvalve member 25', hydraulic iluid under pressure supplied through theconnection Z3 is diverted through a passage 37, non-return valve 38,passage 39 and port 40 through a passage 40a associated with port 101,the fluid under pressure flowing through passages 18 and 17 to the ramcylinder 6. A relief valve 41 loaded by means of a spring 42 limits themaximum pressure in the system.

The valve member 16 is operable through a lever 43, either by the manualcontrol 45a for lifting or lowering, or by movement of thedraft-responsive member, i.e. the bell crank lever 9, against thereaction spring v11, acting through a rod 47 connected to the lever 43by a pin and slot connection 46, 47a. The lower end of the lever 4,3 isconnected to the valve lmember 16 through a pin and slot connection 51.A lever member 52a rigidly conneoted to the crank 44 is provided with aprojection 52 which :coasts with the lever 43 when the shaft 45 is movedanti-clockwise by means of a manually controlled lever 45a. Any suitablefriction means is provided for maintaining the control lever 45a in theposition to which it is set against any force exerted by the draftcontrol mechanism. The lost-motion provided Iby the slot 47a enables thelever 43 to swing about the axis of the crank 44 of lthe control shaft45 against the action of the spring Sti to move the valve member 16 tothe right whereby, in the manner described above, the by-pass valvemember 25 is allowed to iclose and pressure liuid admitted to the ramcylinder for exerting lift.

atroces A link 37 is pivoted at 88 to a lever 39 depending from, andpivoted at 93a to, a projection 9i? on the control valve unit 13, and atthe other end is provided with a roller 91 ycoacting with a cam, such asthe cam S1, mounted on the power lift cross-shaft 2. The link S7 can beswung upwards or downwards about the pivot 8S by means comprising acrank 79 having a crank pin d3 engaging a slot 814- in the link, thecrank being fixed to a shaft Si? operable by a control lever 812.

As shown in FIG. 4, the control valve unit 13 comprises an auxiliarypiston valve member @Z which is normally urged towards the left by aspring 93 so that a projecting end portion 94 of the valve member 92abuts the lower end 86 of the lever S9. A land 92a of the piston valvemember 92 controls a port 9S. Normally, when automatic draft control isin operation and the link 87 is in an inoperative position where it isVswung down so that .the roller 91 cannot be contacted by the earn 81,the piston `valve member 92 is positioned `by contact of the land 92awith a washer 96 held in place by a circlip 9,7, and the port 95 isopen. The port 19 ywith which the land 1Gb of the main control valvemember er1-operates, is thus in communication with Ithe port 95 througha passage 98, while the port 95 is in communication with the passage 18through a passage 99 surrounding an intermediate reduced portion of fthepiston valve member 92', a port 160, passage 101 and passage M2.

Frictional positioning means is provided for the control lever 82.

The operation of the arrangement shown in the draw-r 'in-'gs is asfollows: If ythe control lever 82 is moved antic'lockwise so -that thelink 87 is swung down to a lowermost position, the roller 91 cannot becontacted by the cam 81 and the automatic draft control mechanism willfunction under the control of the lever 45a. If, however, it is desiredto operate with the implement at a selected depth, the control lever 82is positioned so that :when the control lever 45a is Imoved clockwise:from its neutral position -to lower the implement, the implement fallsto a depth corresponding to the setting of the lever 82, the cam 81contacting the roller 91 and moving the link S7 to the right to operatethe auxiliary piston valve member 92 to shut off return flow of tiuidfrom the ram cylinder Ithrough the port 19 which is uncovered by ythepiston member 16 when the lever 45a is set to lower. If the controllever 32 :is then moved anti-clockwise, the implement will followmovement of the lever 82 and fall farther until the cam 81 again acts tomove ythe auxiliary piston valve member l92 to shut off the port 95.Movement of the control lever S2 in the clockwise direc-tion from thesetting for the selected depth lhas no effect as regards lifting theimplement, lifting and lowering of the implement being controlled by thelever 45a acting through the lever d3 on the main control valve member16 in the manner `before described. if the lever 45a is set at the'pointwhere lowering commences, 'a relatively light draft load ywill -besuicient to over-ride the depthlimiting control so that the valve member16 is operated to raise the implement and thereby reduce .the draft.Lifting of the implement from the depth determined by the setting of thecontrol lever 82 causes the cam 81 to retract relatively =to the roller91 so that the auxiliary piston valve member 92 moves to open the port95. Thus, when the draft is reduced suiiiciently for the yautomaticdraft control mechanism to operate in the reverse direction to rnove themain control valve member v1o t0 the implement-lowering position, thepot 95, being open, permits return ilow of iiuid .from the ram cylinderuntil the port 91S is again shut off by the action of the cam S1 whenthe implement reaches the depth determined by the setting of the control-lever 32. If the control lever 45a is moved clockwise to the positioncorresponding to full depth setting when operating with automatic draftcontrol, the draft necessary to cause the automatic draft controlmechanism to over-ride 1the depth-limiting control will be so great thatover-riding will never occur. Between these two limits there is a widerange in which the amount of draft load necessary to cause the automaticdraft control mechanism to over-ride the depth-limiting control isvariable at will. The general effect of the arrangement is to enable animplement to be o erated at a selected depth determined by the settingof the lever S2 and providing means whereby an increase in depth,together with an increase in draft will be prevented until conditionsreturn to normal, whereupon the imp-lement is returned to the selecteddepth setting.

By the arrangement described, one control leve-r, S2, iis operable tobring the depth-limiting control into action `for the selection of apredetermined working depth, while the other lever, 45a, controlslifting land lowering of the implement and also enables the 4automaticdraft control mechanism to be brought into action, if desired, totoverride the action of the depth-limiting control to a variable degreewhich can be selected at the will of the operator.

It will be appreciated that the maintenance of the implement-attachinglinkage in the pre-selected position determined by the setting of thelever 82 normally depends on fluid-tightness of the land 92a of thevalve member 92 in the bore constituted by the passage 99. However, dueto manufacturing tolerances, the clearance between the land 92a and thepassage 99 may be Vsuiicient to allow hydraulic iiuid to leak from theram cylinder, and continued leakage at this point will allow the linkageto move downwards from the selected position. ln order to safeguardagainst this possibility, the control valve means is provided with acircumferential groove in the land 92a of the valve member 92, thegroove 194 communicating through a radial passage and axial passage 166discharging into the reservoir through a radial passage 167. Anadditional port 103 communicates through a passage 34 with the space 33behind the piston 29 operating the bypass valve 25. The passage 34 alsocommunicates with the po1t 35 through an annular groove 10S. The groove1M is so arranged in relation to the port 193 that if leakage occurslafter the land 92a has shut olf the port 95, the groove 104 will comeinto line with .the port 1% and thus allow hydraulic iiuid to escapefrom the space 33 by way of the passage 34, port 103 and passages 105,196, 107. Relief of pressure in the space 33 allows the piston 29 tomove back so that the by-pass valve 25 closes, and pressure uid is thendiverted from the passage 24 through the pressure-regulating valve 38and passage den which communicates directly Wi-th the passage 101 andthence with the passage 18. Lifting will continue until the groove 104is again displaced to the left suilciently to close the port 103communicating with the space 33. Build-up of pressure in the space 33through the passage 31 then causes the piston 29 to open the by-passvalve 25 to restore the low pressure by-pass condition. Thus, animplement supported by the linkage will be held at the position set bythe lever S2 irrespective of any leakage winch may occur.

If the lever S2 is moved anti-clockwise the implementattaching linkagewill fall to a lower position provided that the main valve member 16 isin the lowering position with the land 16h uncovering the port 19.Lifting of the linkage is effected by moving the main valve member 16 tothe lifting position in which the port 19 is closed and the port 35opened. Ilf the main valve member 16 is left at the lowering position,movement of the lever S2 clockwise in the normal manner will not resultin liftling of the linkage. Lifting by use of lthe lever 82 can only beaccomplished by moving the lever clockwise in small increments or at arate corresponding to the lifting movement, so that the groove 164 iskept more or less in register with the port 103. This, however, would beimpracticable and lifting of the linkage is therefore effected by thelever 45a operating on the main valve member 16.

lt will be understood that the invention is not limited to theparticular embodiment hereinbefore described, For example, the controlvalve means may be constructed in any other suitable manner within thescope of the appended claims.

=I claim;

1. In a device of the class described, an implement position controlassembly including a draft responsive means and a hitch position controloperator and hitch operating ram means connected with the operator andmovable with the operator, a pump delivering uid, a reservoir`communicative with the pump, bypass means from the pump to thereservoir having an open position diverting fluid from the pump to thereservoir `and a close position diverting the uid to the ram means formovement of .the ram means, conduit means operatively connected with thebypass means and having a predetermined pressure maintaining the bypassmeans in an open position, control valve means on the device operativelyassociated with the draft responsive means and ram means and operativeof the ram means, means mounted on the device being provided withlinkage disposed in movement reflection relationship between theoperator and the control valve means, said control valve meanscomprising a passage means between the ram means and the reservoir andrst and second interconnected valve means, said rst valve means beingoperatively `connected with the draft responsive means and said secondvalve means operatively engaging with said linkage and movable therewithin the passage means from a rst to a second position and the passagemeans having iiuid under a predetermined pressure between the secondvalve means and the ram means holding the ram means lixed in the firstposition of the second valve means, said second Valve means having uiddischarge means tto the reservoir selectively communicating with theconduit means `and having flow control means in the iirst position ofthe second valve means operatively blocking communication of saidconduit means with the uid dischrge means and communicating the pumpwith the reservoir by Way of the bypass means and upon a loss of uid inthe passage means with `consequential movement of the ram means andoperator and the second valve means to the second position communicatingthe uid discharge means with the conduit means reducing the pressure inthe conduit means and communicating the pump with the ram means. i

2. In a device of the class described, an implement position controlassembly including a hitch position control operator and hitch operatingram means connected with the operator and movable with the operator, apump delivering fluid, `a reservoir communicative with the pump, bypassmeans from the pump to the reservoir having an open position divertinguid from the pump to the reservoir and a close position diverting thefluid to the ram means for movement of the ram means, conduit meansoperatively connected with .the bypass means and having a predeterminedpressure maintaining the bypass means in an open position, control meanson ythe device operatively associated with the ram means and operativeof the ram means, means mounted on the device being provided withlinkage disposed in movement reliection relationship between theoperator and the control means, said control means comprising a passagemeans between the ram means and the reservoir and valve meansoperatively engaging with said linkage yand movable therewith in thepassage means from a rst to a second position and the passage meanshaving fluid under a predetermined pressure between the valve means andthe ram means holding ythe ram means fixed in the first position of thevalve means, said valve means having fluid discharge means to thereservoir selectively `comrmlnicating with the conduit means and havingow control means in the first position of the valve means operativelyblocking communication of said conduit means with lthe uid dischargemeans and communicating the pump with the reservoir by way of the bypassmeans and upon a loss of fluid in the passage means with consequentialmovement of the ram means and operator and the valve means to the secondposition communicating the uid discharge means with the conduit meansreducing the pressure in the conduit means and communicating the pumpwith the ram means.

3. The invention according to claim 2 and said linkage including a linkhaving roller means at one end and engaging with .the valve means at theother end, and said controlled operator comprising cam means havingengagement with the roller means.

4. The invention according to claim 2 and said valve means comprising avalve member in ,the passage means, and the discharge means ytoreservoir comprising a passage in the valve member communicating withthe conduit means in the second position of the valve means.

References Cited in the le of this patent UNITED STATES PATENTS

1. IN A DEVICE OF THE CLASS DESCRIBED, AN IMPLEMENT POSITION CONTROLASSEMBLY INCLUDING A DRAFT RESPONSIVE MEANS AND A HITCH POSITION CONTROLOPERATOR AND HITCH OPERATING RAM MEANS CONNECTED WITH THE OPERATOR ANDMOVABLE WITH THE OPERATOR, A PUMP DELIVERING FLUID, A RESERVOIRCOMMUNICATIVE WITH THE PUMP, BYPASS MEANS FROM THE PUMP TO THE RESERVOIRHAVING AN OPEN POSITION DIVERTING FLUID FROM THE PUMP TO THE RESERVOIRAND A CLOSE POSITION DIVERTING THE FLUID TO THE RAM MEANS FOR MOVEMENTOF THE RAM MEANS, CONDUIT MEANS OPERATIVELY CONNECTED WITH THE BYPASSMEANS AND HAVING A PREDETERMINED PRESSURE MAINTAINING THE BYPASS MEANSIN AN OPEN POSITION, CONTROL VALVE MEANS ON THE DEVICE OPERATIVELYASSOCIATED WITH THE DRAFT RESPONSIVE MEANS AND RAM MEANS AND OPERATIVEOF THE RAM MEANS, MEANS MOUNTED ON THE DEVICE BEING PROVIDED WITHLINKAGE DISPOSED IN MOVEMENT REFLECTION RELATIONSHIP BETWEEN THEOPERATOR AND THE CONTROL VALVE MEANS, SAID CONTROL VALVE MEANSCOMPRISING A PASSAGE MEANS BETWEEN THE RAM MEANS AND THE RESERVOIR ANDFIRST AND SECOND INTERCONNECTED VALVE MEANS, SAID FIRST VALVE MEANSBEING OPERATIVELY CONNECTED WITH THE DRAFT RESPONSIVE MEANS AND SAIDSECOND VALVE MEANS OPERATIVELY ENGAGING WITH SAID LINKAGE AND MOVABLETHEREWITH IN THE PASSAGE MEANS FROM A FIRST TO A SECOND POSITION AND THEPASSAGE MEANS